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BASICS OF REMOTE SENSING
Remote sensing Science and art that permits us to obtain information about an object or phenomenon or area through the analysis of data acquired by a sensing device without its being in contact with that object or phenomenon or area.
Advantages of Remote sensing
- Remote sensing technique provide the synoptic view of large areas.
- The data are collected on a permanent basis.
- The data are an unbiased record of the objects.
- The data are amenable for multi-disciplinary use i.e. the same data can be used for studies in forestry, soil science, hydrology and geology.
- The process of data acquisition and analysis is faster
- Satellite data are received periodically and helps in updating the information and monitoring the changes at short intervals.
- This have unique capability of recording data in visible, as well as invisible parts of electromagnetic spectrum.
Basic processes of remote sensing
The two basic processes involved are
- Data acquisition and
- Data analysis
The elements of the data acquisition process are energy sources, propagation of energy through the atmosphere, energy interaction with earth surface features, re-transmission of energy through the atmosphere, air borne and / or space borne sensors, resulting in the generation of sensor data in pictorial and / ori digital form. In short we use sensors to record variations in the way earth surface features reflect and emit electromagnetic energy.
The data analysis process involves examining data using various viewing and interpretation devices to analyze pictorial data and / or a computer to analyse digital sensor data. Reference data about the resources being studied (such as soil maps, crop statistics and field check data) are used when and where available to aquist in the data analysis. With the aid of the reference data, the analysis extracts information about the type, extent, location and condition of the various resources over which the sensor data were collected. This information is then complied, generally in the form of hard copy maps and tables or as computer files that can be merged with other “layers” of information’s in a geographic information system (GIS). Finally the information is presented to the users who apply it to their decisions –making process.
Remote sensing – Platforms
Platforms play a vital role in remote sense data acquisition. Platforms may be airborne or space borne depending upon the objects under study on earth surface as also on the sensors employed. Air borne platforms: e.g. Balloons, Aircraft, rockets. Balloons: These are designed and used for specific projects. Though the use of balloons is commonly restricted by meteorological factors such as wind velocity, direction etc. their application in resource mapping has been significantly useful.
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